Marine engines of assorted designs including both two cycle and four cycle motors have been utilized with marine craft of various designs over the years. Still further, various drive systems have been coupled to these marine motors, including various propeller and screw arrangements. More recently, in the last several decades, water jet propulsion systems have been utilized widely in watercraft of various types and in particular in small personal watercraft having lengths frequently less then ten feet. In connection with such water jet propulsion systems, two cycle water cooled marine engines are frequently employed.
Water jet propulsion systems, have many advantages over more traditional propulsion systems on watercraft inasmuch as that boats utilizing same can often maneuver in aquatic environments where more traditional propulsion systems which have propellers, would have difficulty. For example, many larger water jet propelled boats have very shallow drafts and are often utilized to shuttle passengers, such as hunters into distance back-country wilderness areas where they may be dropped off for fishing and hunting trips. In these environments, guides may maneuver these boats in shallow rivers and streams and land, or beach the boats at various locations without fear of damaging the associated propulsion systems.
Simply put, a water jet propulsion system discharges a high velocity jet stream of water which reacts with the surrounding aquatic environment to propel the hull of the watercraft through the water. In a boat which is equipped with a water jet propulsion system, the jet unit is mounted in-board of the aft section of the boat hull. Water enters the jet unit near the bottom of the hull and is thereafter accelerated through the jet unit and out through the transom of the boat at high velocity. A prior art jet propulsion system is shown in FIGS. 1 and 2. The steering of the boat is achieved by changing the direction of the stream of water as it leaves the transom of the boat. In this regard, pointing the jet stream in one direction forces the stern of the boat in the opposite direction and causes the vessel to turn. Still further, reverse is achieved by lowering a stern deflector into the jet stream after it leaves the transom. This reverses the direction of the force generated by the jet stream forward and downward and causes the boat to be propelled in a stern direction. In order to utilize a water jet propulsion system, the marine engine must drive the jet unit at a relatively high RPM in order to impart sufficient energy to an impeller which produces the required propulsion for the watercraft. Consequently, two cycle marine motors have been found useful for these purposes.
While the propulsion systems and two cycle marine motors which have been utilized heretofore have operated with a great deal of success, there are shortcomings attendant with their designs. For example, these aforementioned two cycle marine motors which are associated with these propulsion systems are water cooled. More specifically, these two cycle marine motors withdraw water from the body of water upon which the watercraft is resting, and thereafter supplies this water to the two cycle marine motor for cooling. In view of the nature of the operation of a two cycle marine motor, the time with which this cooling water remains within the marine engine is limited. Water exiting the marine engine after cooling same frequently departs the marine engine at a temperature of about 60° F. to about 80° F. This heated water is subsequently returned to the ambient environment.
In view of this arrangement, there has been no convenient means provided heretofore where the heat energy generated by the marine motor during operation can be converted into a source of heat energy which could be imparted to a heater unit, which might radiate heat energy to the occupants of the watercraft. This is particularly desirable when boats of this design are utilized to shuttle passengers during inclement weather or at times when the ambient air temperature is extremely low.
Therefore, a heater and a method for delivering heat energy from a water cooled two cycled marine engine is the subject matter of the present application.